Automatic guided vehicles (AGVs) are well known in the field of material handling systems. AGVs generally navigate by following reflective tape or energized wires installed along the path of the AGVs. One particular type of AGV uses a laser beam to sight unique landmarks such as bar code targets and using triangulation determines the present location. Such AGVs capable of operating without the need for reflective tape or energized wires, such as the laser guided AGV discussed above, are called free ranging AGVs.
Development over the years has expanded the capabilities of the AGV, and greatly increased its utility and flexibility. As a result an AGV is capable of operating in more material handling applications than ever before. One typical material handling task previously restricted to an operator driven material handling vehicle is the loading and unloading of truck trailers. The present invention allows AGVs to load and unload trailers, or any mobile structure not fixed to a location.
Free ranging AGVs have a definite advantage over the AGVs which follow reflective tapes or energized wires when used in the truck trailer loading application. The reflective tape which is used as a guidepath for the AGV, is adhered to the docking bay floor and the trailer bed. Because the tape guidepath must be generally continuous, the trailer bed segment of the reflective tape must be aligned with the tape segment on the dock platform to form an unbroken path. This limitation requires an excessive number of trailer parking manipulations and adjustments to align the segments of the path. Further, the reflective tape is easily damaged or soiled by traffic, which is not tolerated by the AGV optical guidance system.
The guidewire method of vehicle guidance has generally the same alignment problems as the optical tape method in addition to installation and feasibility problems. This method required installing a wire in the trailer bed and providing a means of energizing it.
The instant invention is directed toward the loading and unloading of truck trailers or any mobile structure that is not fixed in location or is not a permanent part of the facility with an AGV.